bash-completion: Use grep -E instead of deprecated egrep
bash-completion: Update command and option lists, sort in same order as --help
refactor: concentrate Repo.hawkey_repo construction in Repo.__init__().
repo: simplify how things are propagated to repo.hawkey_repo.

This is a legit use for __setattr__ as overriding Repo.cost and turning it
into a property makes the cost Option blow up up the chain (Config.optionobj()
no longer sees the cost attribute as an option).
Repo priorities. (RhBug:1048973)
Repo.__setattr__ has to use the parsed value.
depsolving: doesn't install both architectures of pkg by filename (RhBug:1100946)